feat(acp): forward meta/locations fields and use parentToolUseId for precise Agent child grouping

Forward the previously-dropped `locations` and `meta` fields from ACP
SDK ToolCall/ToolCallUpdate events through to the frontend. The meta
field carries `claudeCode.parentToolUseId` which enables precise
parent-child matching for concurrent Agent tool calls during streaming.

- Forward locations/meta in Rust AcpEvent types and connection handlers
- Use parentToolUseId for exact agent→child mapping, with position-based
  fallback for agents that don't provide it (Codex, OpenCode)
- Replace `any` types with proper ToolCallMeta / unknown types
- Add runtime guards for meta field parsing (defensive against
  unexpected shapes from different agents)
- Cache inferLiveToolName results per tool_call_id to avoid redundant
  computation across Phase 1 and Phase 2
- Lazy-construct agentStats only when children exist

src-tauri/src/acp/connection.rs

@@ -1554,6 +1554,8 @@ fn emit_terminal_output_update(
             raw_input: None,
             raw_output: Some(output),
             raw_output_append: Some(append),
+            locations: None,
+            meta: None,
         },
     );
 }
@@ -2501,6 +2503,12 @@ fn emit_conversation_update(
                 .map(|text| resolve_live_tool_input(&text, cwd));
             let raw_output = json_value_to_text(&tc.raw_output)
                 .map(|text| structurize_live_output(&text));
+            let locations = if tc.locations.is_empty() {
+                None
+            } else {
+                serde_json::to_value(&tc.locations).ok()
+            };
+            let meta = tc.meta.map(serde_json::Value::Object);
             crate::web::event_bridge::emit_event(
                 emitter,
                 "acp://event",
@@ -2513,6 +2521,8 @@ fn emit_conversation_update(
                     content,
                     raw_input,
                     raw_output,
+                    locations,
+                    meta,
                 },
             );
         }
@@ -2526,6 +2536,13 @@ fn emit_conversation_update(
                 .map(|text| resolve_live_tool_input(&text, cwd));
             let raw_output = json_value_to_text(&tcu.fields.raw_output)
                 .map(|text| structurize_live_output(&text));
+            let locations = tcu
+                .fields
+                .locations
+                .as_ref()
+                .filter(|l| !l.is_empty())
+                .and_then(|l| serde_json::to_value(l).ok());
+            let meta = tcu.meta.clone().map(serde_json::Value::Object);
             crate::web::event_bridge::emit_event(
                 emitter,
                 "acp://event",
@@ -2538,6 +2555,8 @@ fn emit_conversation_update(
                     raw_input,
                     raw_output,
                     raw_output_append: None,
+                    locations,
+                    meta,
                 },
             );
         }

src-tauri/src/acp/types.rs

@@ -63,6 +63,10 @@ pub enum AcpEvent {
         content: Option<String>,
         raw_input: Option<String>,
         raw_output: Option<String>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        locations: Option<serde_json::Value>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        meta: Option<serde_json::Value>,
     },
     /// Tool call status/content updated
     ToolCallUpdate {
@@ -75,6 +79,10 @@ pub enum AcpEvent {
         raw_output: Option<String>,
         #[serde(skip_serializing_if = "Option::is_none")]
         raw_output_append: Option<bool>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        locations: Option<serde_json::Value>,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        meta: Option<serde_json::Value>,
     },
     /// Agent requests permission
     PermissionRequest {

src/contexts/acp-connections-context.tsx

@@ -55,6 +55,9 @@ import { useFolderContext } from "@/contexts/folder-context"
 
 // ── Shared types (re-exported for consumers) ──
 
+/** ACP extensibility metadata attached to tool calls. */
+export type ToolCallMeta = Record<string, unknown> | null
+
 export interface ToolCallInfo {
   tool_call_id: string
   title: string
@@ -64,6 +67,8 @@ export interface ToolCallInfo {
   raw_input: string | null
   raw_output_chunks: string[]
   raw_output_total_bytes: number
+  locations: unknown
+  meta: ToolCallMeta
 }
 
 export interface PendingPermission {
@@ -149,6 +154,8 @@ type Action =
       content: string | null
       raw_input: string | null
       raw_output: string | null
+      locations: unknown
+      meta: ToolCallMeta
     }
   | {
       type: "TOOL_CALL_UPDATE"
@@ -162,6 +169,8 @@ type Action =
       raw_input: string | null
       raw_output: string | null
       raw_output_append?: boolean
+      locations: unknown
+      meta: ToolCallMeta
     }
   | {
       type: "BATCH_TOOL_CALL_UPDATES"
@@ -176,6 +185,10 @@ type Action =
         raw_input: string | null
         raw_output: string | null
         raw_output_append?: boolean
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        locations: any | null
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        meta: any | null
       }>
     }
   | {
@@ -740,6 +753,8 @@ function connectionsReducer(
               raw_output_chunks:
                 action.raw_output !== null ? [action.raw_output] : [],
               raw_output_total_bytes: action.raw_output?.length ?? 0,
+              locations: action.locations ?? null,
+              meta: action.meta ?? null,
             },
           },
         ]
@@ -781,6 +796,8 @@ function connectionsReducer(
               raw_input: action.raw_input,
               raw_output_chunks: initialChunks,
               raw_output_total_bytes: initialBytes,
+              locations: action.locations ?? null,
+              meta: action.meta ?? null,
             },
           },
         ]
@@ -835,6 +852,8 @@ function connectionsReducer(
               content: action.content ?? block.info.content,
               raw_input: action.raw_input ?? block.info.raw_input,
               raw_output_chunks: newChunks,
+              locations: action.locations ?? block.info.locations,
+              meta: action.meta ?? block.info.meta,
               raw_output_total_bytes: newTotalBytes,
             },
           },
@@ -919,6 +938,8 @@ function connectionsReducer(
                   raw_input: permissionToolInput,
                   raw_output_chunks: [],
                   raw_output_total_bytes: 0,
+                  locations: null,
+                  meta: null,
                 },
               },
             ],
@@ -1598,6 +1619,8 @@ export function AcpConnectionsProvider({ children }: { children: ReactNode }) {
       raw_input: string | null
       raw_output: string | null
       raw_output_append?: boolean
+      locations: unknown
+      meta: ToolCallMeta
     }>
   >([])
   const toolCallUpdateRafId = useRef<number | null>(null)
@@ -1666,6 +1689,8 @@ export function AcpConnectionsProvider({ children }: { children: ReactNode }) {
             content: e.content,
             raw_input: e.raw_input,
             raw_output: e.raw_output,
+            locations: e.locations ?? null,
+            meta: (e.meta as ToolCallMeta) ?? null,
           })
           break
         case "tool_call_update":
@@ -1681,6 +1706,8 @@ export function AcpConnectionsProvider({ children }: { children: ReactNode }) {
             raw_input: e.raw_input,
             raw_output: e.raw_output,
             raw_output_append: e.raw_output_append,
+            locations: e.locations ?? null,
+            meta: (e.meta as ToolCallMeta) ?? null,
           })
           scheduleToolCallUpdateFlush()
           break

src/contexts/conversation-runtime-context.tsx

@@ -255,53 +255,80 @@ function buildStreamingTurnsFromLiveMessage(
   liveMessage: LiveMessage
 ): BuiltStreamingTurns {
   // ── Phase 1: Identify agent → child relationships ──────────────────
-  // Position-based grouping: non-agent tool_calls after agent N (until
+  // Uses meta.claudeCode.parentToolUseId when available (precise), with
-  // the next agent or a content boundary) belong to agent N. When a new
+  // position-based fallback for agents that don't provide it.
-  // "agent" tool_call appears it starts a new capture region, so children
-  // between agent N and agent N+1 go to N. For concurrent agents (both
-  // starting before any children) the last agent receives all children —
-  // imperfect, but the DB-backed parser corrects it on the next refresh.
   const agentChildren = new Map<
     string,
     Array<{ info: ToolCallInfo; toolName: string }>
   >()
   const childToolCallIds = new Set<string>()
 
-  // NOTE: The ACP SDK does not provide parent-child relationships between
+  // Cache inferred tool names — inferLiveToolName is called per tool_call
-  // tool calls — there is no parent_id or context_id. When multiple agents
+  // in both Phase 1 and Phase 2; caching avoids redundant computation.
-  // run concurrently, all their child tool calls appear AFTER both agent
+  const inferredNames = new Map<string, string>()
-  // blocks in the content array, making it impossible to determine which
+  const getToolName = (info: ToolCallInfo): string => {
-  // child belongs to which agent during streaming. The position-based
+    const cached = inferredNames.get(info.tool_call_id)
-  // heuristic below assigns children to the most recent preceding agent.
+    if (cached !== undefined) return cached
-  // The DB-backed parser corrects the grouping on the next data refresh.
+    const name = inferLiveToolName({
-  let activeAgentId: string | null = null
+      title: info.title,
-  let activeAgentCompleted = false
+      kind: info.kind,
+      rawInput: info.raw_input,
+    })
+    inferredNames.set(info.tool_call_id, name)
+    return name
+  }
+
+  // First pass: register all agent tool_call IDs
+  const agentIds = new Set<string>()
+  for (const block of liveMessage.content) {
+    if (block.type !== "tool_call") continue
+    if (getToolName(block.info) === "agent") {
+      agentIds.add(block.info.tool_call_id)
+      agentChildren.set(block.info.tool_call_id, [])
+    }
+  }
+
+  // Second pass: assign children using parentToolUseId or position fallback
+  let positionalAgentId: string | null = null
+  let positionalAgentCompleted = false
 
   for (const block of liveMessage.content) {
     if (block.type === "tool_call") {
-      const toolName = inferLiveToolName({
+      const toolName = getToolName(block.info)
-        title: block.info.title,
-        kind: block.info.kind,
-        rawInput: block.info.raw_input,
-      })
 
       if (toolName === "agent") {
-        // New agent boundary — starts a new capture region
+        positionalAgentId = block.info.tool_call_id
-        activeAgentId = block.info.tool_call_id
+        positionalAgentCompleted =
-        if (!agentChildren.has(activeAgentId)) {
-          agentChildren.set(activeAgentId, [])
-        }
-        activeAgentCompleted =
           block.info.status === "completed" || block.info.status === "failed"
-      } else if (activeAgentId) {
+      } else {
-        childToolCallIds.add(block.info.tool_call_id)
+        // Extract parentToolUseId from ACP meta (Claude Code embeds this
-        agentChildren.get(activeAgentId)!.push({ info: block.info, toolName })
+        // under meta.claudeCode.parentToolUseId). Guard each access level
+        // to avoid crashes on unexpected shapes from other agents.
+        const meta = block.info.meta
+        let parentId: string | undefined
+        if (meta && typeof meta === "object" && "claudeCode" in meta) {
+          const cc = (meta as Record<string, unknown>).claudeCode
+          if (cc && typeof cc === "object" && "parentToolUseId" in cc) {
+            const pid = (cc as Record<string, unknown>).parentToolUseId
+            if (typeof pid === "string") parentId = pid
           }
-    } else if (activeAgentId && activeAgentCompleted) {
+        }
+
+        const resolvedParent =
+          parentId && agentIds.has(parentId) ? parentId : positionalAgentId // fallback
+
+        if (resolvedParent) {
+          childToolCallIds.add(block.info.tool_call_id)
+          agentChildren
+            .get(resolvedParent)!
+            .push({ info: block.info, toolName })
+        }
+      }
+    } else if (positionalAgentId && positionalAgentCompleted) {
       // A text/thinking/plan block after a completed agent means the main
-      // agent is producing new content — stop capturing children.
+      // agent is producing new content — stop position-based capture.
-      activeAgentId = null
+      positionalAgentId = null
-      activeAgentCompleted = false
+      positionalAgentCompleted = false
     }
   }
 
@@ -349,11 +376,7 @@ function buildStreamingTurnsFromLiveMessage(
         // Skip child tool calls — they are nested inside Agent cards
         if (childToolCallIds.has(block.info.tool_call_id)) break
 
-        const toolName = inferLiveToolName({
+        const toolName = getToolName(block.info)
-          title: block.info.title,
-          kind: block.info.kind,
-          rawInput: block.info.raw_input,
-        })
         currentBlocks.push({
           type: "tool_use",
           tool_use_id: block.info.tool_call_id,
@@ -376,7 +399,9 @@ function buildStreamingTurnsFromLiveMessage(
         const children = isAgent
           ? (agentChildren.get(block.info.tool_call_id) ?? [])
           : []
-        const agentStats: AgentExecutionStats | undefined = isAgent
+        // Lazy: only construct agentStats when there are children to show
+        const agentStats: AgentExecutionStats | undefined =
+          isAgent && children.length > 0
             ? {
                 tool_calls: children.map(({ info: ci, toolName: cn }) => {
                   const cFinal =

src/lib/types.ts

@@ -402,6 +402,8 @@ export type AcpEvent =
       content: string | null
       raw_input: string | null
       raw_output: string | null
+      locations?: unknown
+      meta?: unknown
     }
   | {
       type: "tool_call_update"
@@ -413,6 +415,8 @@ export type AcpEvent =
       raw_input: string | null
       raw_output: string | null
       raw_output_append?: boolean
+      locations?: unknown
+      meta?: unknown
     }
   | {
       type: "permission_request"